System and method of pointed position detection, presentation system, and program

ABSTRACT

A system and method of pointed position detection, a presentation system, and a program that make it possible to detect a pointed position accurately. The system of the present invention which detects a position of a light spot that has been projected into an image display region by using an infrared pointer comprises: a CCD camera that picks up an image of this image display region; a pointing coordinate detection section that is position detection means which detects a pointed position of the light spot within the image display region; and a receiver section which receive a state signal that is transmitted from the infrared pointer during a pointer operation by that infrared pointer. The pointing coordinate detection section detects a position of the light spot as the pointed position on the image display region, based on the reception timing of the state signal.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a system and method of pointedposition detection, a presentation system, and also a program.

[0003] 2. Description of Related Art

[0004] There are systems that enable presentations in which a pointerimplement is used to project a light spot onto a screen.

[0005] With such a system, erroneous recognition can occur during theextraction of the light spot from an image signal of an image pick-upmeans when infrared light is used as the light spot, due to thesurrounding environment, more specifically, due to external light suchas an infrared remote controller signal used for controlling theprojector or sunlight intruding from the exterior.

SUMMARY OF THE INVENTION

[0006] The present invention was devised in the light of the abovedescribed technical problem and has as an objective thereof theprovision of a system and method of pointed position detection, apresentation system, and also a program that make it possible to detecta position accurately without any recognition errors, when it comes todetecting the position of a light spot that has been projected onto ascreen or the like, from an image signal of an image pick-up means.

[0007] (1) In order to solve the above described technical problem,there is provided a pointed position detection system in accordance withthe present invention which detects a position of a light spot that isprojected into an image display region by using a pointer implement, thepointed position detection system comprising:

[0008] image pick-up means which picks up an image of the image displayregion;

[0009] position detection means which detects a pointed position of thelight spot within the picked-up image display region; and

[0010] receiver means which receives a state signal transmitted in fromthe pointer implement during a pointing operation performed by thepointer implement;

[0011] wherein the position detection means detects a position of thelight spot as a pointed position in the image display region, based onreception timing of the state signal.

[0012] (2) According to the present invention, there is provided apointed position detection system which detects a position of a lightspot that is projected into an image display region by using a pointerimplement, the pointed position detection system comprising:

[0013] image pick-up section which picks up an image of the imagedisplay region;

[0014] position detection section which detects a pointed position ofthe light spot within the picked-up image display region; and

[0015] receiver section which receives a state signal transmitted infrom the pointer implement during a pointing operation performed by thepointer implement;

[0016] wherein the position detection section detects a position of thelight spot as a pointed position in the image display region, based onreception timing of the state signal.

[0017] (3) According to the present invention, there is provided aprogram embodied on an information storage medium or in a carrier wavefor detecting a position of a light spot that is projected into an imagedisplay region by using a pointer implement, the program implementing ina computer:

[0018] position detection means which detects a pointed position of thelight spot within the image display region, based on an image signalfrom an image pick-up means which picks up an image of the image displayregion; and

[0019] means for causing a receiver means to receive a state signal thatis transmitted in from the pointer implement during a pointing operationperformed by the pointer implement;

[0020] wherein the position detection means detects a position of thelight spot as a pointed position in the image display region, based onreception timing of the state signal.

[0021] (4) According to the present invention, there is provided apointed position detection method of detecting a position of a lightspot that is projected into an image display region by using a pointerimplement, the method comprising:

[0022] an image picking-up step of picking up an image of the imagedisplay region;

[0023] a position detection step of detecting a pointed position of thelight spot within the picked-up image display region; and

[0024] a reception step of receiving a state signal transmitted in fromthe pointer implement during a pointing operation performed by thepointer implement;

[0025] wherein the position detection step detects a position of thelight spot as a pointed position in the image display region, based onreception timing of the state signal.

[0026] In addition to enabling detection of the position of the lightspot by image processing based on the imaging result, the presentinvention makes it possible to detect the pointed position fromconsideration of timing that is indicated by the pointer implement inpractice by using the state signal, thus enabling a reduction inerroneous recognition due to external light such as sunlight or from aremote controller that also uses infrared light, which enables anincrease in the reliability of pointed position detection.

[0027] (5) In each of the pointed position detection system and program,the position detection means may perform correction calculations in thedetection of the pointed position, based on pointed position data for aplurality of frames.

[0028] (6) The position detection step may perform correctioncalculations in the detection of the pointed position, based on pointedposition data for a plurality of frames.

[0029] The precision of position detection is generally determined bythe frame rate and it is difficult to detect the pointed position at aninterval that is shorter than a sampling interval of the image pick-upmeans. The employment of a configuration that performs correctioncalculations ensures a higher detection precision, because thecorrection calculations ensure that the detection of the true pointedposition is based on sampling points before and after the time of theactual pointing operation, even when the pointing is done at a timingthat does not match the sampling timing.

[0030] Note that various methods could be applied to these correctioncalculations, such as linear interpolation or curve interpolation.

[0031] (7) In each of the pointed position detection system and program,the position detection means may perform correction calculations in thedetection of the pointed position that are based on delay time datawhich indicates a delay time comprising at least one of a processingdelay time and a transfer delay time up until the detection of the statesignal.

[0032] (8) The position detection step may perform correctioncalculations in the detection of the pointed position that are based ondelay time data which indicates a delay time comprising at least one ofa processing delay time and a transfer delay time up until the detectionof the state signal.

[0033] This aspect of the invention ensures accurate position detection,by correction calculations that take into consideration any delaybetween the time at which the operating section is actually operated andthe time at which the state signal is received.

[0034] (9) In each of the pointed position detection system, pointedposition detection method, and program, the pointer implement maycomprise:

[0035] light spot projection means which projects the light spot when apredetermined operating section is operated; and

[0036] transmitter means which transmits the state signal insynchronization with the projection of the light spot.

[0037] Since this aspect of the invention makes it possible to use acommon operating section, such as a switch, to project the light spotand also send a state signal at substantially the same time, it enablesthe operator to use the system with a minimum of effort, in comparisonwith a device that is provided with an operating section for the lightspot and a separate operating section for the state signal.

[0038] (10) In this pointed position detection system, the state signalmay comprise an identification signal for the pointer implement; and

[0039] the pointed position detection system may further compriseidentification means which identifies the pointer implement, based onthe identification signal for the pointer implement.

[0040] (11) In the program of the invention, the state signal maycomprise an identification signal for the pointer implement; and

[0041] the program may further implement in a computer, identificationmeans which identifies the pointer implement, based on theidentification signal for the pointer implement.

[0042] This aspect of the invention enables a wide range of differenttypes of presentation because it makes it possible to identify eachpointer implement, even if one person is using a plurality of pointerimplements or two or more people are using a plurality of pointerimplements.

[0043] (12) In each of the pointed position detection system andprogram, the transmitter means may transmit the state signal in awireless fashion; and

[0044] the receiver means may receive the state signal in a wirelessfashion.

[0045] This aspect of the invention makes it easier for the operator touse the system because the use of wireless means to transfer the statesignal removes the need for any cables or the like for transferringsignals.

[0046] (13) The program may further implement in a computer:

[0047] means for causing an image display means to display an image inthe image display region; and

[0048] processing means which performs processing in which a pointedposition detected by the position detection means is reflected inpredetermined data processing.

[0049] This aspect of the invention makes it possible to perform varioustypes of processing.

[0050] (14) According to the present invention, there is provided apresentation system for performing a presentation in which a light spotis projected by a pointer implement into an image display region, thepresentation system comprising:

[0051] display means which displays an image in the image displayregion;

[0052] the above-described pointed position detection system; and

[0053] processing means which performs processing in which a pointedposition detected by the position detection means is reflected inpredetermined data processing.

[0054] In addition to enabling detection of the position of the lightspot by image processing based on the imaging result, the presentinvention makes it possible to detect the pointed position fromconsideration of timing that is indicated by the pointer implement inpractice by using the state signal, thus enabling a reduction inerroneous recognition due to external light such as sunlight or from aremote controller that also uses infrared light, which enables anincrease in the reliability of pointed position detection. This enablesthe presenter to give the presentation while indicating the images incomfort, with no erroneous recognition of the pointed position.

[0055] Note that the data processing could also be applied tocalculation of the cursor display position, changes in the display ofthe cursor, icon pointing determination processing, or icon displaymodification, by way of example.

[0056] (15) In each of the presentation system and program, theprocessing means may perform position control of a cursor comprisedwithin the display image, based on the detected pointed position.

[0057] (16) The pointed position detection method may further comprisesa step of performing position control of a cursor comprised within thedisplay image, based on the detected pointed position.

[0058] This aspect of the invention enables control over the position atwhich a cursor is displayed, relating to the pointed position. Thismakes it possible for the cursor to follow the pointed positionaccurately during the presentation, with no erroneous recognition due toexternal light, thus enabling more effective presentations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0059]FIG. 1 is a schematic view of a presentation system of a typicalembodiment of the present invention;

[0060]FIG. 2 is a schematic diagram of the relationship between pointedposition and cursor display position;

[0061]FIG. 3 is a functional block diagram of the infrared pointer inaccordance with an example of this embodiment of the present invention;

[0062]FIG. 4 is a functional block diagram of the system in accordancewith an example of this embodiment of the present invention;

[0063]FIG. 5 is a schematic diagram of reception timing;

[0064]FIG. 6 is a flowchart of coordinate correction processing; and

[0065]FIG. 7 is illustrative of the hardware configuration of theprocessing section in accordance with this embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0066] The description below relates to an embodiment of the presentinvention applied to a system for determining the pointed position in apresentation system, with reference to the accompanying figures.

[0067] A schematic view of the presentation system in accordance with anexample of this embodiment of the present invention is shown in FIG. 1.

[0068]FIG. 1 shows an example of a presentation system that uses afront-projection device as an image display device.

[0069] A projector 20 that is provided substantially facing a screen 10projects an image for a predetermined presentation onto the screen 10which is a projection surface. An image display region 12 is defined bya display image region formed by this projection of an image. Apresenter 30 gives a presentation to an audience while using an infraredpointer 50 or the like to point to a desired pointed position of animage in the image display region 12.

[0070] As shown in FIG. 1, a CCD camera 40 which functions as an imagepick-up means and which is provided substantially facing the imagedisplay region 12 picks up an image of the image display region 12 ofthe screen 10.

[0071] When giving the presentation, the presenter 30 does so whileprojecting a light spot 310 from the infrared pointer 50 to indicated adesired pointed position on the image display region 12 of the projectedimage.

[0072] The CCD camera 40 takes an image of this situation. Thethus-taken image comprises the image display region 12 and the shadowand actual image of part of the presenter 30 and the infrared pointer50.

[0073] This system performs image processing to detect the light spot310 projected from the infrared pointer 50 of the presenter 30, from thethus-formed image. This specifies the pointed position that is theprojection position of the light spot 310.

[0074] The system can also perform predetermined data processing basedon this detection result. An example of such data processing is cursorcontrol.

[0075] A schematic diagram of the relationship between pointed positionand cursor display position is shown in FIG. 2.

[0076] If the presenter 30 uses the infrared pointer 50 to point to adesired position on the image display region 12, as shown in FIG. 2 byway of example, a cursor 200 within the display image on the imagedisplay region 12 moves to follow the pointed position of the infraredpointer 50.

[0077] With this form of cursor control, it is necessary that thepointed position is detected accurately, to ensure that there is nodiscrepancy between the cursor 200 and the pointed position.

[0078] However, if the location at which the presentation is given issuch that external light such as sunlight or from a remote controllerthat also uses infrared light is projected into the image display region12, that light might cause incorrect recognition of the light from theinfrared pointer 50 and it may not be possible to detect the pointedposition accurately.

[0079] With this embodiment of the invention, the infrared pointer 50outputs a state signal to indicate a state in which it is projecting thelight spot. This system is configured to identify projection timing anddetect a suitable pointed position, by the reception of that statesignal by a receiver section 60 that is connected to the projector 20The description now turns to function blocks for implementing such asystem.

[0080] A functional block diagram of the infrared pointer 50 inaccordance with an example of this embodiment of the present inventionis shown in FIG. 3.

[0081] The infrared pointer 50 comprises an operating section 52, alight-emitting section 54 that is a light spot projection means forprojecting a light spot when the operating section 52 is operating, anda transmitter section 56 for transmitting that state signal insynchronization with the projection of that light spot.

[0082] More specifically, the operating section 52 is a switch or thelike, the light-emitting section 54 is an infrared LED or the like, andthe transmitter section 56 is implemented by a means of transmittingelectromagnetic waves, by way of example. In this embodiment of thepresent invention, the transmitter section 56 comprises a device fortransmitting extremely weak electromagnetic waves, which is in generaluse.

[0083] The light-emitting section 54 and the transmitter section 56generate the light spot and transmit the state signal whenever theswitch of the operating section 52 is pressed, but do not generate thelight nor transmit the signal when the switch is not pressed.

[0084] Since the generation of the light spot and the transmission ofthe state signal are synchronized in this manner, the system thatreceives the state signal can determine that the infrared pointer 50 iscurrently generating the light spot, from the reception of that statesignal.

[0085] The description now turns to the system that receives the statesignal.

[0086] A functional block diagram of a system in accordance with anexample of this embodiment of the invention is shown in FIG. 4.

[0087] This system comprises the receiver section 60 that receives thestate signal from the infrared pointer 50, the CCD camera 40 that is theimage pick-up means, a processing section 110 that performspredetermined processing that is based on an image signal and the statesignal, and the projector 20.

[0088] The processing section 110 comprises a binarizing section 112, apointing coordinate detection section 116, a computation section 118,and a storage section 114. It is preferable that this processing section110 is implemented in a hardware manner by the use of circuitry or thelike, but it could also be implemented by hardware that uses softwaresuch as programs. More specifically, the processing section 110 isimplemented by using components such as a CPU, a ROM that is aninformation storage medium for storing various programs and data, and aRAM that functions as a work area. Details of this hardware are givenlater.

[0089] An image signal that is output from the CCD camera 40 is input tothe binarizing section 112. In this embodiment of the invention, assumethat the CCD camera 40 outputs a monochrome image signal.

[0090] In this embodiment of the present invention, the binarizingsection 112 compares the image signal and a predetermined referencevalue Vref, then extracts a detection target that is the shadow oractual image of the pointing image from the picked-up image, and thepointing coordinate detection section 116 functions as a positiondetection means for detecting the pointed position.

[0091] The binarizing section 112 compares the brightness data of theimage signal that is output from the CCD camera 40 and the referencevalue Vref and performs processing to extract the detection target ofthe pointing image from the image taken by the CCD camera 40. Thebinarizing section 112 outputs that processing data as digital imagedata to the pointing coordinate detection section 116.

[0092] The pointing coordinate detection section 116 extracts a lump ofthe detection target from the digital image data that is output from thebinarizing section 112, then detects the coordinates of the center ofthat detection target lump by calculating the center of gravity thereof.The pointing coordinate detection section 116 takes those centercoordinates as the pointed position that the infrared pointer 50 isindicating, and outputs that detection result to the computation section118.

[0093] The computation section 118 performs various types of dataprocessing and image processing, based on the detection data of thepointed position that is input in this manner.

[0094] Note that further details such as those of the above describedbinarization are disclosed in the patent literature (Japanese PatentPublication No. 11-345085) by the present applicants, so furtherdescription thereof is omitted.

[0095] In this embodiment of the present invention, the computationsection 118 functions as a camera control section 122, a cursor controlsection 120, a correction computation section 124, and a state signalidentification section 126.

[0096] The camera control section 122 performs various types of opticalcontrol such as focus control for the CCD camera 40, based oninformation that is output from the CCD camera 40.

[0097] The cursor control section 120 performs position control for thearrow-shaped cursor 200 that is projected for display in the imagedisplay region 12 in such a manner that it indicates the detectedpointed position. In other words, the cursor control section 120controls an image generation section 128 in such a manner that thecursor 200 that is comprised within the image projected from theprojector 20 moves to follow the pointed position of the infraredpointer 50.

[0098] The receiver section 60 receives a state signal from thetransmitter section 56. In this embodiment of the present invention, thetransmission and reception of the state signal is done by wirelessmeans. This makes it easy for the presenter 30 to give the presentation,because no cables or the like are used. Note that the state signal couldalso be transferred by cable means.

[0099] The state signal identification section 126 identifies the statesignal that is sent by the transmitter section 56 of the infraredpointer 50 and received by the receiver section 60. The state signalindicates that the light spot has been generated and also comprisesinformation for identifying the infrared pointer 50.

[0100] This enables a wide range of different types of presentationbecause it makes it possible to identify each pointer implement, even ifone person is using a plurality of infrared pointers 50 or the like aspointer implements or two or more people are using a plurality ofpointer implements.

[0101] The description now turns to pointed position detectionprocessing, using the above described components.

[0102] A schematic view of reception timing is shown in FIG. 5.

[0103] Factors that must be considered if the state signal is to betransmitted and received by wireless means, as described above, aretransfer delays and processing delays.

[0104] As shown in FIG. 5, this system processes an image in frame unitsthat are taken at times t0, t1, etc . . . , within a predeterminedinterval Δtf. In this case, Δtf is the frame rate so that 30 frames areprocessed in one second, by way of example. This Δtf is approximately 33milliseconds.

[0105] For that reason, up to 33 milliseconds of discrepancy can occurwith the normal detection precision, even when the pointed position isdetected with the greatest precision, and thus errors can occur in thepointed position detection result if the pointed position is determinedwhile the infrared pointer 50 is moving.

[0106] To increase the detection precision, this system performscorrection calculations on the pointed position that are based onpointed position data for a plurality of detection frames.

[0107] In general, the intervals for position detection sampling dependon the frame rate, making it difficult to detect the position atintervals less than the sampling interval. This ensures that thedetection of the true pointed position is based on sampling pointsbefore and after the time of the actual pointing operation, even whenthe pointing is done at a timing that does not match the samplingtiming, thus increasing the detection precision further.

[0108] To increase the detection precision even further, it is necessaryto absorb any discrepancy between the timing at which the operatingsection 52 is pressed and the timing at which the state signal isreceived.

[0109] This system stores the value of a delay time Δt which is thetotal of the transfer delay time created by the discrepancy between thetiming at which the operating section 52 is pressed and the timing atwhich the state signal is received, plus the processing delay time, asdelay time data 129 in the storage section 114.

[0110] This system also stores coordinates (x0, y0), (x1, y1), etc. ofthe detected pointed position in each of a plurality of frames insuccession as detected position data 127 in the storage section 114.

[0111] The correction computation section 124 uses the detected positiondata 127 and the delay time data 129 to perform correction calculationsfor the coordinates of the pointed position that is obtained when thestate signal is identified.

[0112] This makes it possible to increase the detection precision byperforming correction calculations that consider any delay between thetime at which the operating section 52 is operated and the time at whichthe state signal is received, thus ensuring accurate position detection.

[0113] Note that Δte in FIG. 5 denotes the period during which theinfrared pointer 50 generates light. In this embodiment of the presentinvention, one light generation period (Δte) of the infrared pointer 50causes the generation of light during at least two frame periods (2Δtf)of the CCD camera 40, including an allowance for the transfer delay Δt.In other words, the length of two frame periods (2Δtf) is no more thanthe length of one light generation period (Δte) of the infrared pointer50.

[0114] The description now turns to the flow of coordinate correctionprocessing.

[0115] A flowchart of this coordinate correction processing is shown inFIG. 6.

[0116] First of all, the receiver section 60 receives the state signal(step S2) and the state signal identification section 126 identifies thestate signal.

[0117] When state signal has been received and identified, thecorrection computation section 124 calculates the switch determinationtiming (step S4).

[0118] More specifically, the correction computation section 124 obtainsthe difference between a time td at which the state signal was receivedand identified and the delay time 66 t, to obtain the time point tt atwhich the switch was actually pressed.

[0119] The correction computation section 124 then obtains the truecoordinates (xt, yt), based on that time tt (step S6).

[0120] If the frame rate is Δtf, byway of example, xt is obtained from{x0+(tt−t0)*(x1−x0)/Δtf} and yt is similarly obtained from{y0+(tt−t0)*(y1−y0)/Δtf}. These calculations are also performed by thecorrection computation section 124.

[0121] The true coordinates (xt, yt) are obtained as described above.This makes it possible to detect the pointed position in a strictfashion, enabling accurate control even when cursor control isperformed.

[0122] A linear interpolation method can be used in the above describedmethod of calculating corrections, but it is also possible to apply acurve interpolation method thereto if the pointed position moves in acurve.

[0123] Note that if there is no delay, Δt=0 so that the true coordinates(xt, yt) are obtained by a method similar to the calculation method usedwhen there is a delay, but with tt=td.

[0124] The description now turns to the hardware configuration used toimplement the above described processing section 110.

[0125] The hardware of the processing section 110 in accordance with anexample of this embodiment of the invention is shown in FIG. 7.

[0126] In the device shown in this figure, a CPU 1000, ROM 1002, RAM1004, an information storage medium 1006, an image generation IC 1010,and input-output (I/O) ports 1020-1, 1020-2, and 1020-3 are connectedtogether by a system bus 1016 in such a manner that data can be mutuallytransferred therebetween. Components such as the CCD camera 40, theprojector 20, and the receiver section 60 are connected to the I/O ports1020-1, 1020-2, and 1020-3.

[0127] The information storage medium 1006 is used for storing a programand image data. Various means could be used as the information storagemedium 1006, such as a CD-ROM, DVD-ROM, ROM, RAM, or hard disk.

[0128] The CPU 1000 controls the entire device and performs varioustypes of data processing, in accordance with a program stored in theinformation storage medium 1006 and a program stored in the ROM 1002.The RAM 1004 is storage means that is used as a work area for the CPU1000, and given contents for the information storage medium 1006 and theROM 1002, as well as calculation results for the CPU 1000, are containedtherein. A data structure having the logical configuration forimplementing this embodiment of the present invention is constructedwithin the RAM 1002 or the information storage medium 1006.

[0129] The various processes described with reference to FIGS. 1 to 6are implemented by the information storage medium 1006 that containsprograms for performing those processes, together with components suchas the CPU 1000 and the image generation IC 1010 that operate inaccordance with those programs. Note that the processing performed bythe image generation IC 1010 and other components could be implementedin a software manner by the CPU 1000 or an ordinary DSP or the like.

[0130] It is also possible to implement the functions of the processingsection 110 by downloading programs through a network from a hostmachine, instead of using the information storage medium 1006. In otherwords, this system could be embodied by a program for implementation ona computer or by carrier waves.

[0131] The present invention has been described above with reference toa preferred embodiment thereof, but the embodiments of the presentinvention are not limited to the above described specific embodiment.

[0132] For example, this embodiment of the present invention wasdescribed as using a pointer that generates infrared light as thepointer implement, but it can also used for accurately detecting apointed position caused by the operation described with reference toFIG. 5, when using a pointer that generates visible light.

[0133] In addition, the CCD camera 40, the receiver section 60, and theprocessing section 110 could be integrated with the projector 20.

[0134] The data processing after the detection of the pointed positionis also not limited to the calculation of the display position of thecursor; it could also be changes in the display of the cursor, iconpointer determination processing, or icon display modification, by wayof example.

[0135] If the configuration is such that the transmitter section 56transmits the state signal if the operating section 52 has not operated,it is possible to make the correction computation section 124 computethe coordinates of the pointed position at the time at which the statesignal is no longer received.

[0136] The present invention can also be applied to presentations andother performances that display an image by display means other than aprojector means such as the above described projector. Such a displaymeans corresponds to a wide range of display devices other than aliquid-crystal projector, such as a cathode ray tube (CRT), a plasmadisplay panel (PDP), a field emission display (FED), anelectro-luminescence (EL) device, a direct-view type of liquid-crystaldisplay device, or a digital micromirror device (DMD). Note that DMD isa trademark owned by Texas Instruments Incorporated.

[0137] In addition, although the embodiment of the present invention wasdescribed above as being applied to a front-projection type ofprojector, it can equally well be applied to a rear-projection type ofprojector.

What is claimed is:
 1. A pointed position detection system which detectsa position of a light spot that is projected into an image displayregion by using a pointer implement, the pointed position detectionsystem comprising: image pick-up means which picks up an image of theimage display region; position detection means which detects a pointedposition of the light spot within the picked-up image display region;and receiver means which receives a state signal transmitted in from thepointer implement during a pointing operation performed by the pointerimplement; wherein the position detection means detects a position ofthe light spot as a pointed position in the image display region, basedon reception timing of the state signal.
 2. The pointed positiondetection system as defined in claim 1 , wherein the position detectionmeans performs correction calculations in the detection of the pointedposition, based on pointed position data for a plurality of frames. 3.The pointed position detection system as defined in claim 1 , whereinthe position detection means performs correction calculations in thedetection of the pointed position that are based on delay time datawhich indicates a delay time comprising at least one of a processingdelay time and a transfer delay time up until the detection of the statesignal.
 4. The pointed position detection system as defined in claim 1 ,wherein the pointer implement comprises: light spot projection meanswhich projects the light spot when a predetermined operating section isoperated; and transmitter means which transmits the state signal insynchronization with the projection of the light spot.
 5. The pointedposition detection system as defined in claim 4 , wherein: the statesignal comprises an identification signal for the pointer implement; andthe pointed position detection system further comprises identificationmeans which identifies the pointer implement, based on theidentification signal for the pointer implement.
 6. The pointed positiondetection system as defined in claim 4 , wherein: the transmitter meanstransmits the state signal in a wireless fashion; and the receiver meansreceives the state signal in a wireless fashion.
 7. A presentationsystem for performing a presentation in which a light spot is projectedby a pointer implement into an image display region, the presentationsystem comprising: display means which displays an image in the imagedisplay region; the pointed position detection system as defined inclaim 1 ; and processing means which performs processing in which apointed position detected by the position detection means is reflectedin predetermined data processing.
 8. A pointed position detection systemwhich detects a position of a light spot that is projected into an imagedisplay region by using a pointer implement, the pointed positiondetection system comprising: image pick-up section which picks up animage of the image display region; position detection section whichdetects a pointed position of the light spot within the picked-up imagedisplay region; and receiver section which receives a state signaltransmitted in from the pointer implement during a pointing operationperformed by the pointer implement; wherein the position detectionsection detects a position of the light spot as a pointed position inthe image display region, based on reception timing of the state signal.9. The presentation system as defined in claim 7 , wherein theprocessing means performs position control of a cursor comprised withina display image, based on the detected pointed position.
 10. A programembodied on an information storage medium or in a carrier wave fordetecting a position of a light spot that is projected into an imagedisplay region by using a pointer implement, the program implementing ina computer: position detection means which detects a pointed position ofthe light spot within the image display region, based on an image signalfrom an image pick-up means which picks up an image of the image displayregion; and means for causing a receiver means to receive a state signalthat is transmitted in from the pointer implement during a pointingoperation performed by the pointer implement; wherein the positiondetection means detects a position of the light spot as a pointedposition in the image display region, based on reception timing of thestate signal.
 11. The program as defined in claim 10 , wherein theposition detection means performs correction calculations in thedetection of the pointed position, based on pointed position data for aplurality of frames.
 12. The program as defined in claim 10 , whereinthe position detection means performs correction calculations in thedetection of the pointed position that are based on delay time datawhich indicates a delay time comprising at least one of a processingdelay time and a transfer delay time up until the detection of the statesignal.
 13. The program as defined in claim 10 , wherein: the statesignal comprises an identification signal for the pointer implement; andthe program further implements in a computer, identification means whichidentifies the pointer implement, based on the identification signal forthe pointer implement.
 14. The program as defined in claim 13 , whereinthe receiver means receives the state signal in a wireless fashion. 15.The program as defined in claim 10 , further implementing in a computer:means for causing an image display means to display an image in theimage display region; and processing means which performs processing inwhich a pointed position detected by the position detection means isreflected in predetermined data processing.
 16. The program as definedin claim 15 , wherein the processing means performs position control ofa cursor comprised within the display image, based on the detectedpointed position.
 17. A pointed position detection method of detecting aposition of a light spot that is projected into an image display regionby using a pointer implement, the method comprising: an image picking-upstep of picking up an image of the image display region; a positiondetection step of detecting a pointed position of the light spot withinthe picked-up image display region; and a reception step of receiving astate signal transmitted in from the pointer implement during a pointingoperation performed by the pointer implement; wherein the positiondetection step detects a position of the light spot as a pointedposition in the image display region, based on reception timing of thestate signal.
 18. The program as defined in claim 17 , wherein theposition detection step performs correction calculations in thedetection of the pointed position, based on pointed position data for aplurality of frames.
 19. The program as defined in claim 17 , whereinthe position detection step performs correction calculations in thedetection of the pointed position that are based on delay time datawhich indicates a delay time comprising at least one of a processingdelay time and a transfer delay time up until the detection of the statesignal.
 20. The program as defined in claim 17 , further comprising: astep of performing position control of a cursor comprised within thedisplay image, based on the detected pointed position.